Ionic currents in gastrointestinal smooth muscle

Summary

Principal Investigator: Hamid I Akbarali
Abstract: DESCRIPTION (provided by applicant): The long term goals of this study are to define the changes in ion channel activity in colonic inflammation. Ulcerative colitis is an inflammatory bowel disease characterized by recurrent episodes of colonic inflammation and tissue degeneration. The overall hypothesis is that inflammation induces specific changes in expression, regulation and kinetics of ion channels in smooth muscle cells. These changes affect gastrointestinal motility contributing to the clinical expression of altered contractions. In this proposal, we will test the hypothesis that reactive nitrogen species produced during colonic inflammation cause nitration of the tyrosine residues within the c-terminus of the calcium channel and result in down-regulation of channel function. Based on our preliminary findings, our working model is that nitration of tyrosine residues within the c-terminus of the Ca2+ channel prevents phosphorylation by c-src kinase and alters channel gating, downstream intracellular signaling and gene transcription. Specific aim 1 is to determine the mechanisms by which c-src kinase alters the gating properties of the smooth muscle calcium channel. In this aim, we will determine the biophysical properties of the calcium channel and examine the effect of tyrosine phosphorylation and nitration on voltage-dependent inactivation using single channel and whole-cell patch clamp techniques. We will also investigate the interaction of src kinase with the calcium channel using fluorescence resonance energy transfer (FRET) and siRNA approaches to delineate the functional effect of src-Ca2+ channel interaction in muscle contraction. Preliminary data show that mutation of the terminal tyrosine residue within the c-terminus of the Ca2+ channel prevents the docking of the src homology 2 (SH2) domain. In specific aim 2 we will examine the role of nitration of the Ca2+ channel in intracellular signaling and gene expression following inflammation. In this aim we will measure phosphorylation of the transcription factor CREB, and the downstream activation of cyclic AMP response element (CRE). We will test the effect of Ca2+ channel nitration on these processes and define the role of the terminal tyrosine residues using mutants of the Ca2+ channel. Analogous to protein phosphorylation-dephosphorylation, we will test whether denitration is a physiological process in specific aim 3. Our preliminary findings indicate that Ca2+ channel are substrate(s) for denitration. We will test whether denitration reverses the down-regulation of calcium influx in whole tissue segments, and determine the source of denitrating enzymes within the colonic wall. The information obtained from these studies will increase our understanding of the potential changes in ion channel activity with inflammation and help identify novel therapeutic agents in the treatment of motility disturbances in the pathophysiology of the colon. PUBLIC HEALTH RELEVANCE: Colonic inflammation occurs in response to a variety of stimuli and results in smooth muscle dysmotility. Determining the mechanisms of altered protein-protein interaction between ion channels and intracellular signaling molecules are likely to define novel therapeutic approaches targeted at ion channels
Funding Period: 1993-05-01 - 2015-03-31
more information: NIH RePORT

Top Publications

  1. pmc Denitration of L-type calcium channel
    Minho Kang
    Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
    FEBS Lett 582:3033-6. 2008
  2. pmc Increased PDE5 activity and decreased Rho kinase and PKC activities in colonic muscle from caveolin-1-/- mice impair the peristaltic reflex and propulsion
    Sunila Mahavadi
    Box 980551, Dept of Physiology, School of Medicine, Virginia Commonwealth Univ, Richmond, VA 23298 0551
    Am J Physiol Gastrointest Liver Physiol 305:G964-74. 2013
  3. pmc Electrophysiological characteristics of enteric neurons isolated from the immortomouse
    Edward G Hawkins
    Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, 1112 E, Clay Street, McGuire Hall 317, Richmond, VA 23298, USA
    Dig Dis Sci 58:1516-27. 2013
  4. pmc Hydrogen sulfide as an allosteric modulator of ATP-sensitive potassium channels in colonic inflammation
    Aravind R Gade
    Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298 0524, USA
    Mol Pharmacol 83:294-306. 2013
  5. pmc Novel insights on the effect of nicotine in a murine colitis model
    Shakir D Alsharari
    Department of Pharmacology and Toxicology, Virginia Commonwealth University, Box 980613, Richmond, VA 23298 0613, USA
    J Pharmacol Exp Ther 344:207-17. 2013
  6. pmc Morphine decreases enteric neuron excitability via inhibition of sodium channels
    Tricia H Smith
    Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
    PLoS ONE 7:e45251. 2012
  7. pmc Evidence for the putative cannabinoid receptor (GPR55)-mediated inhibitory effects on intestinal contractility in mice
    Gracious R Ross
    Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298 0613, USA
    Pharmacology 90:55-65. 2012
  8. pmc Up-regulation of brain-derived neurotrophic factor in primary afferent pathway regulates colon-to-bladder cross-sensitization in rat
    Chun Mei Xia
    Department of Physiology, Virginia Commonwealth University School of Medicine, 1220 East Broad Street, PO Box 0551, MMRB 5038, VA 23219 Richmond, Virginia, USA
    J Neuroinflammation 9:30. 2012
  9. pmc Prolonged sympathetic innervation of sensory neurons in rat thoracolumbar dorsal root ganglia during chronic colitis
    C M Xia
    Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
    Neurogastroenterol Motil 23:801-e339. 2011
  10. pmc Ion channel remodeling in gastrointestinal inflammation
    H I Akbarali
    Department of Pharmacology and Toxicology, Medical College of Virginia Campus, VCU Program in Enteric Neuromuscular Sciences VPENS, Virginia Commonwealth University, Richmond, VA 23298, USA
    Neurogastroenterol Motil 22:1045-55. 2010

Detail Information

Publications16

  1. pmc Denitration of L-type calcium channel
    Minho Kang
    Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
    FEBS Lett 582:3033-6. 2008
    ..7 cell lysates. These findings indicate that denitration may be a physiological mechanism to restore cellular excitability during inflammation...
  2. pmc Increased PDE5 activity and decreased Rho kinase and PKC activities in colonic muscle from caveolin-1-/- mice impair the peristaltic reflex and propulsion
    Sunila Mahavadi
    Box 980551, Dept of Physiology, School of Medicine, Virginia Commonwealth Univ, Richmond, VA 23298 0551
    Am J Physiol Gastrointest Liver Physiol 305:G964-74. 2013
    ..We conclude that the integrity of caveolae is essential for contractile and relaxant activity in colonic smooth muscle and the maintenance of neuromuscular function at organ level...
  3. pmc Electrophysiological characteristics of enteric neurons isolated from the immortomouse
    Edward G Hawkins
    Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, 1112 E, Clay Street, McGuire Hall 317, Richmond, VA 23298, USA
    Dig Dis Sci 58:1516-27. 2013
    ..However, their electrophysiological properties are not known. The goal of this study was to determine the electrical excitability and ionic conductance of the immortalized postnatal enteric neuronal (IM-PEN) cell line...
  4. pmc Hydrogen sulfide as an allosteric modulator of ATP-sensitive potassium channels in colonic inflammation
    Aravind R Gade
    Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298 0524, USA
    Mol Pharmacol 83:294-306. 2013
    ..Sulfhydration of sulfonylurea receptor 2B (SUR2B) was induced by NaHS and colonic inflammation. These data suggest that sulfhydration of SUR2B induces allosteric modulation of K(ATP) currents in colonic inflammation...
  5. pmc Novel insights on the effect of nicotine in a murine colitis model
    Shakir D Alsharari
    Department of Pharmacology and Toxicology, Virginia Commonwealth University, Box 980613, Richmond, VA 23298 0613, USA
    J Pharmacol Exp Ther 344:207-17. 2013
    ..These results highlight that dose and route of administration play a critical role in the protective effect of nicotine in the DSS mouse colitis model...
  6. pmc Morphine decreases enteric neuron excitability via inhibition of sodium channels
    Tricia H Smith
    Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
    PLoS ONE 7:e45251. 2012
    ..These results demonstrate the feasibility of isolating mouse myenteric neurons and establish sodium channel inhibition as a mechanism for morphine-induced decrease in neuronal excitability...
  7. pmc Evidence for the putative cannabinoid receptor (GPR55)-mediated inhibitory effects on intestinal contractility in mice
    Gracious R Ross
    Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298 0613, USA
    Pharmacology 90:55-65. 2012
    ..Although gene expression of GPR55 is evident in the gut, functional evidence for GPR55 in the gut is unknown. In this study, we tested the hypothesis that GPR55 activation inhibits neurogenic contractions in the gut...
  8. pmc Up-regulation of brain-derived neurotrophic factor in primary afferent pathway regulates colon-to-bladder cross-sensitization in rat
    Chun Mei Xia
    Department of Physiology, Virginia Commonwealth University School of Medicine, 1220 East Broad Street, PO Box 0551, MMRB 5038, VA 23219 Richmond, Virginia, USA
    J Neuroinflammation 9:30. 2012
    ..Studies with animal models have demonstrated that activation of primary afferent pathways may have a role in mediating viscero-visceral cross-organ sensitization...
  9. pmc Prolonged sympathetic innervation of sensory neurons in rat thoracolumbar dorsal root ganglia during chronic colitis
    C M Xia
    Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
    Neurogastroenterol Motil 23:801-e339. 2011
    ..Peripheral irritation-induced sensory plasticity may involve catecholaminergic innervation of sensory neurons in the dorsal root ganglia (DRG)...
  10. pmc Ion channel remodeling in gastrointestinal inflammation
    H I Akbarali
    Department of Pharmacology and Toxicology, Medical College of Virginia Campus, VCU Program in Enteric Neuromuscular Sciences VPENS, Virginia Commonwealth University, Richmond, VA 23298, USA
    Neurogastroenterol Motil 22:1045-55. 2010
    ..Collectively, these findings suggest that inflammation results in electrical remodeling of smooth muscle cells in addition to structural remodeling...
  11. pmc {alpha}7-nAChR-mediated suppression of hyperexcitability of colonic dorsal root ganglia neurons in experimental colitis
    Galya R Abdrakhmanova
    Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, 23298, USA
    Am J Physiol Gastrointest Liver Physiol 299:G761-8. 2010
    ..Overall, our findings suggest that nicotine at low 1 microM concentration suppresses in vitro hyperexcitability of inflamed colonic DRG neurons in a mouse model of acute colonic inflammation via activation of alpha(7)-nAChRs...
  12. pmc Colonic inflammation alters Src kinase-dependent gating properties of single Ca2+ channels via tyrosine nitration
    Gracious R Ross
    Dept of Pharmacology and Toxicology, Virginia Commonwealth Univ, 1112 E Clay St, McGuire Hall 317, Richmond, VA 23298, USA
    Am J Physiol Gastrointest Liver Physiol 298:G976-84. 2010
    ..The present findings suggest that the transition of Ca2+ channels to the noninactivating open state is Src kinase dependent. Tyrosine nitration prevents Src-mediated transitions, leading to decreased calcium currents...
  13. pmc The effect of tyrosine nitration of L-type Ca2+ channels on excitation-transcription coupling in colonic inflammation
    M Kang
    Department of Pharmacology and Toxicology, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, Richmond, VA 23298, USA
    Br J Pharmacol 159:1226-35. 2010
    ..In this study we examined the effect of tyrosine nitration and colonic inflammation on Ca(2+) channel mediated phosphorylation of CREB and CRE activation...
  14. pmc Morphine tolerance in the mouse ileum and colon
    Gracious R Ross
    Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
    J Pharmacol Exp Ther 327:561-72. 2008
    ..Tolerance to morphine developed in the ileum but not the colon upon repeated administration of morphine. These findings indicate that a lack of tolerance development in the colon is the basis for opioid bowel dysfunction...
  15. pmc Brain-derived neurotrophic factor enhances cholinergic contraction of longitudinal muscle of rabbit intestine via activation of phospholipase C
    M Al-Qudah
    Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia
    Am J Physiol Gastrointest Liver Physiol 306:G328-37. 2014
    ..We conclude that exogenous BDNF augments the CCh-induced contraction of longitudinal muscle from rabbit intestine by activating TrkB receptors and subsequent PLC activation. ..

Research Grants30

  1. Control of Vascular Cell Motility by CaMKII
    Harold A Singer; Fiscal Year: 2013
    ....
  2. IBD and Mucosal Inflammation, Immunology, and Microbiology of the GI Tract
    Eugene B Chang; Fiscal Year: 2013
    ..Through its cost-effective, enabling technologies and services, the DDRCC has been a major factor in the advancement of scholarship and discovery in IBD and digestive diseases at the University of Chicago. ..
  3. Purinergic neurotransmission in the gut
    James J Galligan; Fiscal Year: 2013
    ..This information would help to develop new drug treatments for common motility disorders. ..
  4. Redox regulation of phagocyte NOX2 in inflammation and aging
    Robert A Clark; Fiscal Year: 2013
    ....
  5. FoxM1: A molecular target in pancreatic cancer
    Fazlul H Sarkar; Fiscal Year: 2013
    ..We will test our hypothesis by three specific aims using molecular approaches in vitro and by using animal models in vivo (both orthotopic mouse model and transgenic mouse models of PC). ..
  6. Mechanisms/Treatments of Lower Urinary Tract Dysfunction After Spinal Cord Injury
    ANTHONY JOHN KANAI; Fiscal Year: 2013
    ..We are confident that our experience and unique approaches will lead to a very interactive and fruitful program. ..
  7. Excitation contraction coupling in bladder smooth muscle
    Robert S Moreland; Fiscal Year: 2013
    ..The studies proposed in this application will provide this missing information. If we can learn how normal bladder is controlled, we can then design experiments to study and hopefully repair abnormal bladder ..
  8. MITOCHONDRIAL ENCEPHALOMYOPATHIES AND MENTAL RETARDATION
    Salvatore DiMauro; Fiscal Year: 2013
    ....